Stringed musical instruments having a neck and a body are well known. Guitars, bases, banjos, mandolins, violins, Dobros and ukuleles are examples of such stringed instruments.
It is generally desirable that the neck of a stringed musical instrument have a small amount of bowing in the direction in which the strings tend to pull the neck. Such bowing is desirable so as to accommodate the excursion of a played string. As those skilled in the art will appreciate, a played string requires sufficient clearance with respect to the neck of the musical instrument so as to avoid undesirably contacting the neck or frets of the musical instrument as the string moves back and forth about its unplayed or idle position. Generally, the most clearance is required between a string and the neck of the musical instrument along the central portion of the string, where such excursions tend to be the greatest. Such clearance is provided by forming the neck of a musical instrument, such as a guitar, so as to have a very slight bow when the strings are installed and properly tuned.
However, one common problem associated with stringed musical instruments is undesirable bowing or deformation of the neck of the musical instrument. Such deformation of the neck of a musical instrument may be caused by poor workmanship, poor materials, excessive changes in humidity, excessive temperature, excessive changes in temperature, excessive string tension, or by any combination of these factors.
Typically, such deformation of the neck of a stringed musical instrument results in undesirable bowing of the neck, which inhibits proper playing of the musical instrument. Such bowing most frequently occurs in the direction in which the strings tend to pull the neck. However, such bowing may occur in any other direction, including that direction opposite to the direction in which the strings tend to pull the neck, a direction perpendicular to that direction, or any other direction. The neck of a musical instrument may also deform in various other manners, such as by being deformed into a generally S-shaped curve. It is also possible for the neck to twist, such as generally about it longitudinal centerline.
As those skilled in the art will appreciate, that portion of a stringed musical instrument, such as a guitar, where the neck attaches to the body thereof tends to be a weak point, where undesirable bowing commonly occurs. This attachment point can be thought of as defining a hinge about which the neck pivots (although typically only very slightly) relative to the body, so as to permit bowing due to excessive string tension.
Many stringed instruments have a truss rod or tension rod disposed within the neck thereof for adjusting the amount of bow in the neck of the musical instrument. When a musical instrument having such a tension rod bows at the attachment point of the neck to the body thereof, it is common to attempt to compensate for such bowing by adjusting the tension rod so as to cause the neck to bow in a direction opposite that which occurs at the attachment point. Bowing at the attachment point usually occurs in the direction in which the strings pull the neck. Therefore, the tension rod is adjusted (tightened) so as to cause the neck to bow in the direction which is opposite to that in which the strings pull the neck.
However, it must be appreciated that a tension rod adjusts the amount of bow in the neck by varying the curvature of the neck about the center portion of the length of the neck. Thus, such adjustment of the tension rod changes the curvature of the neck by causing the neck to bend about its own center. However, the bowing of the instrument caused at the attachment point of the neck to the body thereof is occurring at the proximal end (attachment end) of the neck, rather than near the center of the length of the neck. Therefore, such an attempt to compensate for bowing at the attachment point of the neck generally results in the introduction of further undesirable deformation of the neck, rather than compensating for the original deformation at the attachment point. This may result in a generally S-shaped curvature of the neck, which may make the musical instrument unplayable.
Although such deformation is typically very small when measured, it is important to appreciate that even a slight amount of deformation may render a stringed musical instrument unplayable. For example, bowing of the neck of a guitar in the direction in which the strings tend to pull the neck results in a greater distance between the strings and the frets for higher pitched notes than for lower pitched notes on a given string. This is the type of bowing which frequently occurs at the attachment point of the neck to the body of a musical instrument, as discussed above. Such bowing inherently requires that a guitar player push higher pitched notes further downward (to the fingerboard) than lower pitched notes. As those skilled in the art will appreciate, pushing the string further downward in order to play a note stretches the string more, thereby increasing the tension on the string and consequently undesirably increasing the pitch of the resulting note. Thus, the higher pitched notes of a guitar having a neck which is bowed in this manner will be pitched too high and will thus be out of tune.
Bowing of the neck of a guitar in the opposite direction from the direction in which the strings tend to pull the neck causes the strings to be closer to the frets for higher pitched notes on a given string than for lower pitched notes on the same string. This type of bowing may occur when the tension rod is over tightened. When a string is too close to a fret, there is a substantial tendency for that string to buzz, wherein the string contracts the fret when played, thereby resulting in a undesired sound.
Poor workmanship may result in undesirable bowing of the neck of a musical instrument. This may occur, for example, if the neck of the musical instrument is incorrectly attached to the body thereof. Thus, if the neck attachment screws are insufficiently tightened, the neck may be permitted to pivot excessively with respect to the body of the musical instrument, thus resulting in undesirable bowing of the neck of the musical instrument, as discussed above.
Additionally, it is possible for the tension rod to be incorrectly adjusted when the musical instrument is initially set up. Under-tightening the tension rod may result in bowing of the neck in the direction in which the strings tend to pull the neck. Over-tightening of the tension rod may result in bowing of the neck away from the direction in which the strings tend to pull the neck.
The use of poor materials, such as uncured or otherwise defective wood for the neck of a stringed musical instrument may result in undesirable bowing or other deformation thereof. For example, uncured wood tends to bend or deform over time as changes in the moisture content of the wood occur. The use of wood which is not sufficiently strong or rigid may permit the strings to pull the neck so as to cause an undesirable bow therein.
Environmental conditions, such as temperature, humidity, excessive cycling or rapid changes in temperature, and excess cycling or rapid changes in humidity are likely to adversely affect the moisture content of the wood from which the neck of a musical instrument is constructed. Such changes in the moisture content of the wood may result in undesirable changes in the shape of the neck, particularly when the neck is subject to string tension which tends to pull the neck in one direction.
A very common cause of bowing of a neck of a stringed musical instrument, such as a guitar, is over-tightening of the strings thereof. As those skilled in the art will appreciate, the more the strings of a guitar are tightened, the more tension the strings apply to the neck of the guitar, so as to urge the neck of the guitar to bend or bow in the direction in which the strings pull the neck.
Deformation of the neck of a musical instrument due to poor workmanship, such as incorrect attachment of the neck to the body of the musical instrument, cannot be properly compensated for with the tension rod, as discussed above.
Deformation of the neck of a musical instrument due to poor materials and/or environmental conditions can generally be compensated for when the deformation is simple. This is, if such deformation merely results in bowing of the neck of the musical instrument, then the tension rod may be effective in compensating for such deformation. However, deformation due to the use of poor materials and/or adverse environmental conditions may result in more complex deformation of the neck of a musical instrument, which cannot be corrected by adjusting the tension rod.
In view of the foregoing, it should be appreciated that although adjustment of the tension rod of a stringed musical instrument may compensate for simple bowing of the neck of a musical instrument when such bowing occurs proximate a center portion of the length to the neck, adjustment of a tension rod is not effective in compensating for other types of deformation of the neck of a stringed musical instrument, such as bowing about the attachment point of the neck and such as complex deformation of the neck.
Moreover, any substantial deformation of the neck of a musical instrument results in an undesirable change in the relative position of the strings with respect to the neck (and, consequently with respect to the frets), frequently in a manner which inhibits proper playing of the musical instrument. As such, it is highly desirable to mitigate such deformation of the neck of a stringed musical instrument.
One contemporary attempt to mitigate such undesirable deformation of the neck of a stringed musical instrument involves the placement of two graphite or metal rails into two longitudinally extending grooves formed substantially along the length of the neck. These rails are placed immediately under the fingerboard. Such graphite or metal rails are inherently rigid and thus tend to resist deformation of the neck of the musical instrument.
However, the use of such metal rails inherently increases the weight of the stringed musical instrument, particularly of the neck thereof. Increasing the weight of a stringed musical instrument, such as a guitar, generally makes the musical instrument less comfortable and more difficult to play. Further, increasing the weight of the neck of such a musical instrument undesirably affects the balance thereof, again generally making the musical instrument less comfortable and more difficult to play.
Additionally, the use of such metal rails undesirably alters the tone of the stringed musical instrument. As those skilled in the art will appreciate, metal is substantially denser than wood and has acoustic properties which are substantially different from those of wood.
It is also known to form a guitar neck of graphite-epoxy composite material. Although such a graphite-epoxy composite guitar neck is very strong and is very resistant to undesirable deformation, the tone of a guitar having a graphite-epoxy composite neck is not desirable.
It is worthwhile to appreciate that the desired tone of a stringed musical instrument is typically a tone which has been historically determined. That is, it is generally desirable for newer stringed musical instruments to mimic the tone of older stringed musical instruments, since it is the older stringed musical instruments which were used to produce the music which we are accustomed to hearing. Therefore, changes in the construction of a stringed musical instrument should typically be made in a manner which does not substantially alter the tone of the musical instrument from that which the buying and listening public has become accustomed to hearing.
Moreover, it has been found that the use of some high strength materials, such as metals, to strengthen the neck of a stringed musical instrument undesirably changes the tone thereof. Therefore, the use of such materials does not provide a satisfactory solution to the problem of undesirable deformation of the neck of stringed musical instruments.
It is also worthwhile to appreciate that a guitar neck should have some flexibility. It is generally desired that a guitar neck have an amount of flexibility which, like tone, has been historically determined. That is, guitar players have become accustomed to the neck of a guitar having some flexibility. Guitar players prefer that the necks of newer guitars likewise have such flexibility. Even though the amount of flexibility of a guitar neck is very small, it does affect the feel and playability of the musical instrument.
The use of graphite or metal rails, as discussed above, undesirably over stiffens the neck of the musical instrument. Similarly, a neck formed of graphite-epoxy composite material is almost completely lacking in flexibility. Therefore, the use of such contemporary graphite or steel rails and the construction of a neck entirely of graphite-epoxy composite material provide a neck which is undesirably stiff.
In view of the foregoing, it is desirable to mitigate deformation of the neck of a stringed musical instrument in a manner which does not substantially increase the weight or alter the balance of the musical instrument and in a manner which does not undesirably alter the tone of the musical instrument or the flexibility of the neck thereof.